Threshold effects in catchment storm response and the occurrence and magnitude of flood events: implications for flood frequency
The aim of this paper is to illustrate the effects of selected catchment storage thresholds upon runoff behaviour, and specifically their impact upon flood frequency. The analysis is carried out with the use of a stochastic rainfall model, incorporating rainfall variability at intra-event, inter-eve...
Main Authors: | , , , |
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Format: | Article |
Language: | English |
Published: |
Copernicus Publications
2007-08-01
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Series: | Hydrology and Earth System Sciences |
Online Access: | http://www.hydrol-earth-syst-sci.net/11/1515/2007/hess-11-1515-2007.pdf |
Summary: | The aim of this paper is to illustrate the effects of selected catchment
storage thresholds upon runoff behaviour, and specifically their impact upon
flood frequency. The analysis is carried out with the use of a stochastic
rainfall model, incorporating rainfall variability at intra-event,
inter-event and seasonal timescales, as well as infrequent summer tropical
cyclones, coupled with deterministic rainfall-runoff models that incorporate
runoff generation by both saturation excess and subsurface stormflow
mechanisms. Changing runoff generation mechanisms (i.e. from subsurface flow
to surface runoff) associated with a given threshold (i.e. saturation
storage capacity) is shown to be manifested in the flood frequency curve as
a break in slope. It is observed that the inclusion of infrequent summer
storm events increases the temporal frequency occurrence and magnitude of
surface runoff events, in this way contributing to steeper flood frequency
curves, and an additional break in the slope of the flood frequency curve.
The results of this study highlight the importance of thresholds on flood
frequency, and provide insights into the complex interactions between
rainfall variability and threshold nonlinearities in the rainfall-runoff
process, which are shown to have a significant impact on the resulting flood
frequency curves. |
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ISSN: | 1027-5606 1607-7938 |